Proving the (imaginary) teacher wrong! (geometry)

In the right angled triangle ADE use the theorem of Pythagorus to find ED.\[ED ^{2}=13^{2}-12^{2}\]

When you find ED you know EF and can work out the length of AB

My calculations don't add up to any of the answers given

What did you get for the length AB?

Here are the answers I am given. But based on what you have said: 12+3.6+12=27.6

So you calculated ED to be 3.6. Did you calculate ED as per the equation I gave earlier?

i messed up! my apologies. I must have done something wrong. I now realize that it should have been 17.7, not 3.6.

No. ED is not 17.7\[ED ^{2}=13^{2}-12^{2}=169-144=25\] \[ED=\sqrt{25}\]

oh my goodness. I am not on my game today.

Do you now understand what the correct choice should be?

Yes I do. Thanks for the help.

You're welcome. Good on you for perservering :)

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